On June 19, the U.S. Supreme Court held in a 7-1 decision that an employer defending a disparate-impact claim under the federal Age Discrimination in Employment Act (ADEA) bears both the burden of production and the burden of persuasion for the "reasonable factors other than age" (RFOA) affirmative defense under the Act. In Meacham v. Knolls Atomic Power Laboratory, the Court observed that a disparate-impact claim assumes that a "non-age factor" was at work. The focus of the RFOA defense is whether that factor was a "reasonable" one for the employer to use.

The Court also clarified that the business necessity test plays no role in ADEA disparate-impact cases. The Court explained that, unlike the business necessity test, which asks whether there are other ways for the employer to achieve its goals that do not result in a disparate impact on a protected class, the reasonableness inquiry includes no such requirement. Therefore, certain employment criteria that are routinely used by employers may be reasonable despite their adverse impact on older workers as a group. (The EEOC had previously issued new rules regarding this issue at 73 Fed. Reg. 16807-16809 (2008).)